Base for electric lamps and similar devices



April 1940- Y w. s. DAVIS ET AL 2.198.934

- am: FOR ELECTRIC Lm'rs AND SIMILAR DEVICES- I Filed March 25, 1939 Fig." 2.

Inventors:

Harry C. Atkins,

Their? Atporney:

William G. Davis,

Patented Apr. 30, 1940 uNirED STATES PA ENT 1 oFFicr. 1

2,198,934 a miss FOR ELECTRIC LAMPS" AND suntan 1 mivrcss William G. Davis'- and Harry CrAtkins, Cleveland Heights, Ohio, assignors toGenei-al Electric'Company, acorporation of New York- Application March 25, 1939, Serial No. 264,154

6 Claims.

, there is a considerable waste of the metallic stock material from which the round blanks are punched,and a corresponding increase in manufacturing cost.

One object of our invention .is to provide an.

. improved method of manufacturing base shells for electric incandescent lamps and similar devices which will eliminate practically all waste of the metallic stock material from which the bases are made and which will effect a material saving in the cost of manufacture.

Another object of our invention is to provide an improved base construction for electric incandescent lamps and similar devices.

Still another object of our invention is to provide an electric lamp base having a shell provided with a longitudinally extending internal lamp seam joint which is discontinued for a short distance inward from the inner edge or rim of the shell to thereby permit proper application of the base onto the lamp bulb neck andin addition to provide a slot through which one of the lamp.

leading-in wires may be led to the outer surface of the shell.

A further object of our invention is to provide an electric lamp base having a shell provided with a plurality of relatively small embossments or protuberances arranged around said shell in the form of a helix with one ormore of the embossments adjacentthe rim of the shell displaced a relatively slight amount from the true line 'of the helix to thereby provide means for lockingthe lamp in its socket.

Further objects and advantages of our invention will appear from the following description of species thereof and from the accompanying drawing, in which:

' Fig. 1 is a longitudinal sectional view of 'an electric incandescent lamp provided with a base comprising our invention; Fig. 2 is an elevation of the lamp shown in Fig, 1 taken at right angles thereto; Fig. 3 is a top view of the blank from same by solder 28,.

l which the base shell comprising ourinvention is made; Fig. 4 is a side view of the base shell blank showing the manner in which the ends thereof are bent preparatory to the formation of the'lap seam joint' therebetween; Figs. 5 to 8 are end views of the base shell blank showing the successive steps involved in rolling the blank into cylindrical shape and securing the abutting ends together by an internal lap seam joint; Fig. 9 is a fragmentary end view, on an enlarged scale, of the base shell showing the completed internal lap seam joint; and Fig. 10 is an enlarged elevation of a finished base shell comprising our invention.

Referring to the drawing, the lamp there shown comprises a glass bulb or envelope l0 having a tapering neck portion II and an electric energy translation elementin the form of ,a coiled or coiled coil filament l2 of refractory metal, preferably tungsten, hermetically sealed therein; The said filament is supported within the bulb by a pair of leading-in wires l3, l4 connected to the opposite ends of the filament and having portions sealed into a pressed portion of a stem It. The filament I2 is further supported, at a point intermediate its ends, by a support wire I! fastened to a cane rod l8 extending longitudinally of the lamp from the stem press l5. Additional support wires I9, l9 extend transversely from said cane rod l8 and engage the leading-in wires l3, l4.

Secured to the neck portion preferably by cement 20, is a base 2| according to our invention. The said base. comprises a metallic shell 22,.preferably of brass and having an inturned flange 23 at its dome end, and a metallic bottom contact eyelet 24 secured to said .shell flange by a suitable insulating medium 25,

such as glass. One leading-in'wire l3 extends through a centrally located hole 26 in the base insulation 25 and is connected to the bottom contact eyelet 24 preferably'by solder 21, while the n of the bulb in.

other leading-in wire I4 is bent back over the neck of the bulb and around the inner extremity or rim of the shell 22 where it is secured to the As shown particularly in Figs; 2 and 10," the interrupted thread for engagement with the .thread of a conventional lamp socket. :The-number andlocation of these protuberances along the line of the helix is immaterial, a sumcient To providje means for locking the base in av socket, one or more of the protuberances 29 at the inner end of the helix, i. e., adjacent the rim 33 of the base shell 22, may be displaced a slight amount, for instance, 0.019 of arrinch or thereabouts, from the true line of the helix. The displacement may be to either side of the line of the helix, i. e., towards the rim' of the base shell or towards the dome thereof, as desired; The displaced protuberances force the other pro-' tuberances against the threads in the lamp socket during the last turn or so of the lamp into its socket. The resulting tight frictional grip between the various base shell protuberances and the lamp socket threads thus provides a form of locking means tending to prevent any unscrewing action of the lamp in its socket which might otherwise result. from vibrations of various nature. The displacement of the protuberances,

' however, should not be so great as to prevent a completelnsertion of the lamp base in its socket, otherwise the bottom center contact of the lamp might not engage with the corresponding socket contact.

The base shell 22 according to the invention .is formed from a blank 30 of metal (Figs. 3-4) which is first stamped with the protuberances 29 out of strip material, then rolled into cylindrical shape, and the abutting ends secured together by an internal lap seam joint 3|, the successive steps being .shown in Figs. 3 to 8. To insure proper fitting or alignment'of the base shell on the tapered neck I of the bulb, and further to provide a slit 32 through which leading-inwire I4 may be led to the outer surface of the base shell, the internal lap seam'3l is discontinued for a relatively short distance inward from the rim "33 of the base shell. For this purpose, the opposite ends of the metal blank 30 are provided'with notches 34, 34 adjacent that edge 33 which eventually forms the rim of the base shell. The leading-in wire ll, outwardly of the base shell .22, is preferably disposed along the lap seam joint 3| and soldered thereto, the solder thus serving to further secure the ends of the metal blank together and to prevent disrupture of the lap seam joint.

The rolling of the metallic blank 30 into cylindrical shape and the formation of the internal lap seam joint 3| is performed by a suitable machine, such as the multi-slid e machine commercially used at present for the production of short lengths of metallic tubing with internal lap seams. As shown in Fig. 9, the lap seam joint 3|, when completed, consists of an inner hook or lip 35, formed by inwardly bending one end of the blank .back upon itself, and interlocked with an inwardly offset hook or lip 33 on the other end of the saidblank Following the formation of the lap seamjoint, the edge 31 of the cylindrical shell is rolled or bent inward to form the flange or dome 23, thus completingthe base shell. It is obviously desirable that none of the protuberances 23 be" formed in the base at the lap seam joint 3|. Instead. they should all be located in spaced relation to said lap seam joint,

otherwise the said joint might interfere with the easy-insertion or threading of the base shell into its socket.

By forming the base shells in the above-delamps. The pins are stamped in the metal blank from which the base shell is made in the same manner as the protuberances 23 referred to above.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A base for electrical devices comprising a shell, said shell consisting of a strip of metal formed in the shape of a cylinder with the abutting ends secured together by an internal lap seam joint and having a plurality of socket-engaging protuberances disposed around its circumference, said protuberances being formedfrom the metal of said shell and being disposed in spaced relation to said lap seam joint.

2. A base for electrical devices comprising a shell, said shell consisting of a strip of metal formed in the shape of a cylinder with the abutting ends secured together by an internal lap seam joint and having aplurality of protuberances disposed around the circumference thereof in the form of a helix and in spaced relation to said lap seam joint.

3. A base for electrical devices comprising a shell having an open end, said shell consisting of a strip of metal formed in the shape of a cylinder with the abutting ends secured together by an internal lap seam joint and having a plurality of protuberances disposed around the circumference thereof in the form of a helix and in spaced relation to said lap seam joint, one or more of said protuberances adjacent the said open end of said shell being offset a slight distance from the true line of the helix.

4. A base for electricaldevices comprising a shell, said shell consisting. of a strip of metal riorly of said bulb, and a base comprising a metallic shell portion secured at its rim to said flared bulb neck, said shell consisting of a strip of metal formed in the shape of a cylinder with the abutting ends secured together by an internal lap seam joint, said lap seam joint being discontinued at a relatively short distance from the rim of said shell-to thereby provide a slit and to permit said rim to uniformly engage said flared bulb neck around the periphery thereof so as to maintain alignment between said shell and bulb neck, one of said leading-in wires extending through said slit and being secured to said shell at said lap seam joint, and said shell having a plurality of socket-engaging protuberances disposed around its circumference.

6. An electrical device comprising a bulb having a flared neck portion,- an electric energy translation element sealed within said bulb, a pair of leading-in wires connected to said electric energy translation element and extending exteriorly of said bulb, and a base secured to said bulb neck and comprising a metallic shell and a bottom contact eyelet secured together by man-- lation, one of said leading-in wires being con- 3 nected to said shell and the other of said leadingin wires being connected to said bottom contact eyelet,,sa.id shell consisting of a strip of metal formed in the shape of a cylinder with the abutting ends secured together by an internal lap seam joint and having a plurality of protuberances disposed around the circumference thereof in the form of a helix and in spaced relation to said lap seam joint.

WILLIAM G. DAVIS. HARRY C.' ATKINS. 

